


Treading unknown Waters

by Nera_Solani



Category: Supernatural
Genre: Coconuts, Creature Castiel, Desert Island, Established Castiel/Dean Winchester, Established Relationship, Fluff, Inspired by Fanfiction, Inspired by “Ensnared”, M/M, POV Outsider, Pirates, Sailor Dean, Siren Castiel, shipwrecked
Language: English
Status: Completed
Published: 2018-04-17
Updated: 2018-04-17
Packaged: 2019-04-24 07:22:00
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,608
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14350665
Author URL: https://archiveofourown.org/users/Nera_Solani/pseuds/Nera_Solani
Summary: When a researcher on mythical creatures goes over board and strands on a desert island, she doesn't expect to get the opportunity to learn more about sirens than anyone ever has.Turns out, they can be a lot more human than most people think...





	Treading unknown Waters

**Author's Note:**

  * For [saltnhalo](https://archiveofourown.org/users/saltnhalo/gifts).
  * Inspired by [Ensnared](https://archiveofourown.org/works/11211444) by [saltnhalo](https://archiveofourown.org/users/saltnhalo/pseuds/saltnhalo). 



> Go read saltnhalo's fic, it's amazing! And this will make a lot more sense if you do, but I suppose it's also readable as a standalone.
> 
> Emma, when you read this, I'm not an AU person, but your work made me want to write one. I applaud you.
> 
> Enjoy!

_Day 1_

I woke up on this empty beach, my clothes soaked with salt water. I remember that our ship was under attack and that I fell over board. I remember clinging to a piece of wood for dear life, trying my best to keep my notebook above water. The sea was freezing cold and when I had closed my eyes, I’d been sure I’d never open them again. But here I am. It will forever be a mystery to me how my notebook stayed dry, but I am endlessly grateful for it. This notebook that accompanied me to many travels contains all my research on mythical creatures of the past couple years. It made me the best known and most respected expert on creatures in the world (even though I’m not a man, would you believe…). It would be terrible if I lost it. And now writing into it gives me comfort as I am all alone on this island it seems.

I wandered around a bit and found a coconut palm tree. It provided food and water for the day, but at some point I should start to explore this island, maybe I’ll find some inhabitants after all. Or at the very least something that isn’t a coconut. Just not today. I feel exhausted and my clothes are heavy with water.

 

_Day 2_

At least my clothes are somewhat dry now, though my shoes are probably ruined. I won’t need them here anyway. I lost my hat when I went overboard. If I survive this, I will get a new one. It’s hot here, but the forest provides shelter from the burning sun.

I started exploring the island and it turns out that things could be worse. There are lots of different edible fruits growing here and I have seen plenty of fish in the water of the surrounding sea. If only I had something more than a dagger with me. But I’ll make do. I’m a scientist after all, I can figure something out.

The island seems to be fairly small. I could probably walk along the entire coast line in one or two hours, but it’s big enough to survive. As I walked along the coast, I suddenly heard voices in the distance. For a moment I thought I was going mad, that the isolation was getting to me, but it’s only been two days, so that would be highly unlikely. And my ears were proven right, there were two people sitting next to a campfire, talking. From my distance I couldn’t see them well and they didn’t seem to notice me, so I hid in the forest and slowly crept closer. They could be pirates for all I knew. But as I got a closer look, hiding behind a thick palm tree, what I saw was even more shocking than any pirate could ever be. Both of the two men were clad only in pants, but one of them had webbed hands and feet, claws and his smile showed sharp teeth. I rifled through all my notes on every creature I know. I have seen something like this before. When I found the note, my eyes surely must’ve widened rather comically. That man is a siren. A real, living siren who was chatting to a — to my knowledge — human man. Fascinating.

I didn’t dare to approach them. Though the siren didn’t seem to consider the other man food, it might not feel the same about me. So I decided to watch them from afar, hidden between the trees. The scientist in me is endlessly intrigued, exhilarated even, but the rest of me is, well, frightened. One the one hand, I might get deep insights into the behavior of sirens like no one ever has before, on the other hand, it’s a **siren**. There is a reason why we don't know much about them. No one who has tried to study them ever came back. I have to take the risk though. First and foremost, I am a researcher. And I don’t even know if I will ever get off this island anyway, so might as well do something useful with my time.

It’s surprising enough that the siren actually speaks English. From my place here in the forest I can’t make out everything they say, but they speak with affection in their voices and fondness on their faces. I managed to catch their names as they talked about expanding their cabin. I can see the impressive construction from here (I should probably build a shelter of my own soon). The human is apparently named Dean, while the siren’s name seems to be Cas. I assume it might be an abbreviation, a nickname of some sort, but I can’t be sure.

 

_Day 3_

I managed to build a provisional shelter, nothing compared to the cabin of the two men. It’s not much, but it’ll suffice for the time being. I found Dean and Cas at their huge cabin again, hunting fish together. Dean with a spear and Cas with his bare hands. The man watches fondly as the siren moves through the water with inhuman speed and agility. I wish I knew how they came to be such close friends. I’m sure it would be an interesting story. But there is something nagging at the back of my mind that protests against the term “friends”. No, the word just doesn’t seem to fit right.

When Cas comes out of the water, fish in both hands and a wide smile on his face — he’s definitely a He, that much I can tell — I find out just why the word felt so wrong. Dean takes a step forward, reaching out to gently cup the siren’s cheek and then he leans down and presses a tender kiss to his lips. Now I wish all the more that I knew how they came to be what they are.

I had to leave them when it started to rain, because I wasn’t fond of the prospect of getting soaked again, so I hid in my shelter and waited for the rain to stop.

 

_Day 4_

I was so caught up watching Dean and his siren that I barely remembered to eat. I collected a fair amount of fruit and other edible plants and even managed to carve myself a primitive spear. It’s a good thing I refused to wear dresses on my travels, pants make everything so much easier… But fishing with a spear is hard and I ended up with only my fruit. Maybe I’ll have better luck next time.

My research is progressing greatly. Dean’s and Cas’ relationship is extraordinary. In all my years of traveling the world I’ve never seen anything like it. It’s built on trust, steadied by devotion, aflame with passion and filled with love. Today I witnessed something that no one in the history of mankind ever has.

Castiel — which turned out to be his full name — had weakened, Dean noticed immediately. He looked pale, his skin grayish and he was wobbly on his feet. Dean rushed to his side to steady him with an expression of worry on his face.

“Cas, are you okay? Do you need to feed?”, he asked his partner. That question sent me into a mild panic and I hid further behind my tree.

The siren made a low, pitiful noise and I dared to look at them again, only to see him nod, holding onto Dean to steady himself.

“Okay,” Dean said and lowered them both gently onto the sand as the sun was setting behind the horizon, dipping everything into beautiful reds and yellows.

When they were both comfortable, Dean pulled Cas into his arms and kissed him deeply. For a moment my mind was filled with confusion, but then I noticed how Castiel visibly grew stronger. They parted and Dean leaned heavily against his siren who now had to support him instead of the other way round. I couldn’t believe my eyes. Dean let Cas feed on him. No one has ever seen a siren feed before — well, at least they didn’t live to tell the tale — but it is widely known that they do so through a bite in the neck. The knowledge that they can apparently also feed through a kiss and that without killing is… I don't know what to call it. A breakthrough maybe? A scientific holy grail in my field? Something like that. The only thing that it is for certain is unexpected.

It’s almost dark now, the sun barely visible on the horizon. The two men are next to their campfire. Castiel is sitting in the sand, cradling Dean’s head in his lap as he sings for him. I’ve never heard a siren’s song, never thought I would and get out of it alive. It certainly lives up to the tales. His voice is deep, the lyrics of the song foreign, the words unfamiliar. His song is beautiful but it doesn’t affect me. He’s not singing for me after all, he’s singing for Dean. The man is curled up on the warm sand, head resting in Castiel’s lap, nuzzling into his stomach. Cas is playing gently with Dean’s hair as he sings and Dean hums softly under the ministrations. I can’t exactly see it from here, but I’m certain that his eyes are closed. Castiel’s eyes are soft and a small smile is evident on his lips. I never knew that sirens could love, but in this moment it is so glaringly obvious that they can. This siren is so much more human than I would’ve ever expected. I wish someone would look at me like that too one day. Dean reaches for Cas’ hand and they lace their fingers together as he continues to listen to his siren’s song, who is singing for him and only him. It’s such an intimate moment that I suddenly feel like an intruder. So I leave them alone, making my way through the dark forest to my shelter.

 

_Day 5_

I found fresh water. In the forest of the island is an area with multiple pools and one of them is filled with water that is drinkable. It’s a relief. Now I won't have to live on coconut water anymore and I can finally wash my clothes a little. I even took a bath in one of the pools, but I made sure to be quick since it’s more than likely that Dean comes here too for water and I don’t want to get surprised while naked.

Dean looks perfectly fine again, no traces of his weakened state from yesterday left. He’s well rested and I even saw him climbing up a palm tree, letting the fruit fall down for Castiel to catch. They’re a remarkable team. It almost seems like there is nothing they can’t accomplish together. I hope that’s true.

I managed to catch a fish today and I lit a small campfire to grill it. I still have no clue how to get off this island.

 

_Day 6_

There are so many things I’d like to ask them, but above all I want to know how two people from such different worlds — a human and a siren — could fall so deeply in love. And I also want to know if Dean landed here the same way I did. I can’t just walk up and ask him, but if I had to guess, I’d put my money on ‘yes’.

I’m pretty sure this island isn’t marked on any map, so the chances of a ship coming by are relatively low, especially since I’m not even sure anyone is looking for me. From the route of our ship I have determined my position as best as I can and there is hope, however small. There is a frequently used trading route not far from here, if I had a small boat, I could reach it. The problem is, there is only one boat on this island that belongs to Dean and Castiel, which is pretty much out of reach for me, since it’s tied down right in front of their cabin, also I’m not sure how far I’d get with it without a siren by my side, and I don't have any tools to cut down trees and build a raft. So I’m still stuck here until I can figure something out to solve this problem.

I caught some more fish today, it seems I’m slowly getting the hang of it. There don't seem to be any other animals on this island though. At least none that I could eat.

When I was watching Dean and Cas again, I was surprised once more. Maybe I should stop being surprised by now after everything I have learned about them in the last couple days, but I just can't help it.

Dean was looking out onto the sea while Cas was restocking on firewood.

Suddenly the man turned towards his siren and called over to him, “Hey, Cas! You hungry?”

The siren perked up at that and Dean chuckled lightly, pointing out at the sea. There I saw it too. A ship in the distance, heading for the trading route. But as I squinted my eyes against the sun to look closer, I saw that it wasn’t a normal ship. It was a pirate ship.

Cas shot Dean a wide grin that showed his perky teeth and then he slipped out of his pants and jumped into the waves. I wish I had a telescope with me to see what happened on that ship. Dean just stood at the shore, waiting for his lover to return.

When he did, my eyes lit up. He brought a small dinghy with him, the oars lying inside as he pushed the boat from behind onto the beach. But oars weren’t the only things inside the dinghy. There were plenty of goods in there. Dean was just staring at it with his mouth fallen open and Cas came out of the water with a bright grin on his face.

“You always complain about not having a proper bed, so I… brought you one,” he explained.

Finally, Dean closed his mouth and managed to say, “I can see that.”

“I brought as many things as I could fit into the boat.”

Now Dean seemed to shake himself out of his stupor and instead broke into a soft, loving smile.

I watched them bring the goods into their home one by one. A bed that was surely big enough for them both, foreign fruit and vegetables, some tools and small furniture, drinking cups and lastly two chickens.

Dean grinned at his siren, “It’ll be nice to get something different than fish for a change.”

Then he pulled Cas in for a kiss, mumbling something that I couldn’t completely make out, but it sounded a lot like, “Taking such good care of me…”

Looking closer at the pirate ship, my hopes grew. It’s not overly big. I could sail it on my own for a short while, just until I reach the trading route…

 

_Day 7_

I am packing as many supplies as I can. Coconuts for water and fruit for food. I made an improvised bag out of palm leaves to carry it all. I have to leave before the wind carries the empty pirate ship too far away from here. Now that my escape is so tangible, I feel remorseful. I’d like to stay just a few days more to watch Dean and Castiel a little longer. I have learned more about sirens in this one week than anyone else in the last century or so. But I don't have a choice. I have to leave now or I might be stuck here forever. Maybe I can come back here one day.

I was at the fresh water pool to drink as I heard them approach. I quickly hid behind a nearby tree without making a noise. It was already getting dark, but I didn’t have a chance to get to the dinghy without being noticed until then.

They were laughing, joking with each other as they approached the big pool where I had taken my baths. Dean undressed and walked into the water, Castiel following suit. They splashed around with loud laughter, so full of joy and life that I couldn’t help but think they had a little piece of paradise on this island. I hope it will forever stay that way for them.

The laughter slowly dissipated and Cas dived down, entirely disappearing under water, only to surface right in front of Dean, both of them smiling as they looked into each other’s eyes for a long moment. Then Dean closed the gap between them and pulled Cas in for a passionate kiss.

Making love with a siren in the water underneath the stars. How poetic. But making love was exactly what they were doing. Never in my life had I believed that creatures could be so tender and yet Castiel had proven me wrong time and time again. I wonder if people on the mainland will even believe me. With my reputation it’s quite possible they would. But I won't publish all of this. I don't have the right to. This love and this island is **theirs** and I won't present it to the world on a silver tablet.

While they were occupied with each other in the pool, I snuck out of the forest, grabbed my provisions and headed for the dinghy. As I pushed it into the water, I cast a last look back at the island that taught me so much, then I rowed towards the ship.

 

Nobody ever asked how I came to be sailing on a pirate ship all on my own after having been lost for an entire week. I sold the ship and kept the gold coins that I had found on it to buy a ship of my own. I call her the Siren’s Song. My newest publication about sirens hit the scientific world like a cannonball. Most of them believe me, some don't. But unless they want to seek out a siren, they can't really prove me wrong.

I am sailing the world again, doing my research as I used to. But now I have a different perspective. Castiel made me stop and reevaluate my view of mythical creatures. They are not evil. Just like humans aren’t evil per default. They feed to stay alive, not to hurt people. They are intelligent, feeling beings.

I drew a small map into my notebook where the Siren Island is marked too. I never told anyone where it is located and I never will. I thought about warning sailors of coming close to it in case Castiel would be hungry, but I didn’t. Many would probably take that warning as an invitation to see it for themselves or even worse, a challenge to kill the creature. No, I will take the location of the island to my grave. I make sure to pass it with my ship every so often, looking through my telescope to check on them and make sure everything is alright. They probably don't need my protection, but I’m willing to provide it anyway.

 

My ship was under attack. We were being chased by pirates. The Siren’s Song is fast, but they were catching up on us. Luckily, I recognized the waters we were sailing and I knew what I had to do. No one knows this part of the ocean better than I do. So I ordered my steersman to make for the small patch of land over there. He was confused but followed my command. I took my telescope and watched the beach of the island closely. There they were, Dean was turned towards Castiel, maybe saying something to him and then the siren jumped into the water.

“Cover your ears!”, I shouted at my crew. The pirate ship was closing up and we were running out of time. When they just stared at me in utter confusion, I yelled louder, “Did I stutter?! Plug your damn ears!!”

They did as they were told and so did I. Not a minute too early as I could hear soft singing, muffled through the earplugs, followed by screams of terror from the pirate ship. When the screams died down, I heard a splash, the cue for me to pull the plugs out of my ears and then I looked over the railing down at the dark water. Suddenly a head came to the surface, bright blue eyes with slitted pupils staring curiously up at me and I just smiled, grabbed my hat with one hand and bowed my head slightly in thanks. Castiel seemed surprised by the gesture, but he nodded back nonetheless before disappearing underneath the waves again. That moment I decided I’ll come back to Siren Island one day and actually talk to Dean and Castiel, but this time I’ll come alone, without my crew, to make sure that their little paradise stays undisturbed. Turning back around I noticed the terrified looks on the faces of my crew, who were still covering their ears in panic, but I just smiled and told them to man up. With that, I gained their respect forever. I told them to loot the pirate ship of anything with worth and then I filled a small bucket with a few selected goods and set it into the water where I knew that a small current would carry it safely to the island’s shore, together with a small handwritten note.

**Author's Note:**

> The tenses got really weird on me in this, I sometimes changed tense in the middle of a sentence and annoyed my amazing beta Zwetschge14 with that. She helped me fix it, I hope it turned out alright.
> 
> If you like it, please leave kudos or a comment, you have no idea how much that means to a writer, seriously!


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